1. Field of the Invention
The present invention relates to an electricity removal apparatus for removing electricity of a charged body that is either positively or negatively charged.
2. Description of Related Art
An electricity removal apparatus, namely an ionizer, which removes the electricity of a charged body by producing positive or negative ions has been known (shown in Japanese Unexamined Patent Publication No. 2000-58290 and Japanese Unexamined Patent Publication No. 2003-86393). The electricity removal apparatus produces ions by a corona discharge onto an electrode needle by applying a high voltage. Thus, the electricity removal apparatus has a problem, wherein the capability of producing the ion, decreases over time as the electrode needle becomes worn away and tainted.
To address the above problem, Japanese Unexamined Patent Publication No. 2003-86393 shows a technique, based on an electricity removal apparatus for alternately producing positive ions and negative ions by applying high voltages having different polarities alternately onto a common electrode needle, for providing an interval during which no voltage is applied on the electrode needle after an application of a positive voltage before an application of a negative voltage, for example, as well as for adjusting a voltage to be applied on the electrode needle so that an ion balance becomes neutral immediately before the interval. As shown in the 2003-86393 publication, providing an interval between the application of voltages having different polarities can reduce the length of actual working hours of the electrode needle, thereby suppressing wear and contamination of the electrode needle as well as maintaining the ion balance appropriately.